Hearing instrument manufacturers have adopted laser scanning of traditional impressions as the method of obtaining mathematical representations of the ear canal geometry. A dispenser will acquire the impression from the patient and mail the impression directly to the manufacturer. Unfortunately, the impression can become distorted during the mailing process due to uncured material and excessive temperatures in the delivery trucks; the result is an inaccurate impression of the patient's physiology thereby leading to a hearing instrument that does not fit properly. It is common practice for the dispenser to acquire another impression from the patient and return the hearing instrument for rework.
In some instances, it is common for the hearing instrument to pop out of the patient's ear during chewing or other jaw motion. Since the impression is obtained in a “static” condition within the ear canal, geometry changes of the ear canal during chewing can cause the hearing instrument to jostle and pop out. In order to mitigate these occurrences, it may be advantageous to acquire two different impressions: one with the jaw closed and one with the jaw open. The final earmold for the hearing instrument can be extrapolated as an average from the two impressions, thereby reducing the potential for “popout”.
Depending on the cure rate of the polymeric material used for ear impressions, the process can typically take from ten to fifteen minutes per pair of impressions, not to mention administrative time in preparing, shipping, and receiving the impressions. It would be advantageous to have a process that acquired the mathematical representation at the dispenser's office in less time and forwarded the data directly to the manufacturer electronically to save time and expense.